This invention relates to the art of detecting and displaying the state of an internal moving medium of a living body, and more particularly to a novel technique which is effectively applicable to an ultrasonic diagnosis apparatus used for measurement and display of the moving speed (referred to hereinafter simply as speed) of an internal moving medium of a living body, the dispersion of the moving speed (referred to hereinafter simply as speed dispersion), the intensity of an ultrasonic beam reflected from the internal moving medium of the living body, etc.
An ultrasonic pulse-Doppler method has been put into practical use for the measurement of the speed of an internal moving part of a living body, for example, a visceral organ such as the heart or a fluid such as blood or humor in a circulatory organ.
A prior art, ultrasonic diagnosis apparatus utilizing the ultrasonic pulse-Doppler method displays three kinds of information of such an internal moving medium, that is, the speed, moving direction and speed dispersion as video or picture information. In the case of actual display, the speed of the moving medium is displayed by relative luminance, and the moving direction of the moving part is displayed by a color selected depending on the direction. Further, for the display of the speed dispersion, a color used for displaying the speed dispersion is mixed with a pre-selected color indicative of the speed in a proportion corresponding to the rate of speed dispersion, thereby displaying the speed dispersion by a color change.
However, in the case of the prior art displaying means, recording of a picture displaying the speed by the luminance is dependent upon the recording characteristics of a recording system. Therefore, the reproducibility of the luminance of a picture signal has not been satisfactory, and it has been nearly impossible to read the speed on the displayed picture or photograph.
Further, in the case of the prior art displaying means, information of the intensity of the ultrasonic wave reflected from the internal moving medium of the living body (the reflected power spectrum) has not been displayed. The reflected ultrasonic wave intensity referred to above corresponds to the flow rate of, for example, blood when the internal moving medium of the living body is blood flow, and is thus a parameter indicative of the rate of motion of the moving medium.
In an apparatus such as, a pulse-Doppler blood flow meter, which is now widely employed in this field and which resorts to the method of high-speed Fourier transformation for displaying the motion of an internal moving medium of a living body, the intensity of an ultrasonic beam reflected from the moving medium is displayed by luminance. Accordingly, displaying the speed by luminance has led to the problem that the speed displayed by the luminance cannot be distinguished from the reflected ultrasonic beam intensity which is also displayed by the luminance in the prior art system, resulting in a possible change of the basis of diagnosis.